posix.c

samba-3.0.22.tar.gz 编译smb服务器的源码

/* 
   Unix SMB/CIFS implementation.
   Locking functions
   Copyright (C) Jeremy Allison 1992-2000
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

   Revision History:

   POSIX locking support. Jeremy Allison ([e-mail]), Apr. 2000.
*/

#include "includes.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_LOCKING

/*
 * The POSIX locking database handle.
 */

static TDB_CONTEXT *posix_lock_tdb;

/*
 * The pending close database handle.
 */

static TDB_CONTEXT *posix_pending_close_tdb;

/*
 * The data in POSIX lock records is an unsorted linear array of these
 * records.  It is unnecessary to store the count as tdb provides the
 * size of the record.
 */

struct posix_lock {
	int fd;
	SMB_OFF_T start;
	SMB_OFF_T size;
	int lock_type;
};

/*
 * The data in POSIX pending close records is an unsorted linear array of int
 * records.  It is unnecessary to store the count as tdb provides the
 * size of the record.
 */

/* The key used in both the POSIX databases. */

struct posix_lock_key {
	SMB_DEV_T device;
	SMB_INO_T inode;
}; 

/*******************************************************************
 Form a static locking key for a dev/inode pair.
******************************************************************/

static TDB_DATA locking_key(SMB_DEV_T dev, SMB_INO_T inode)
{
	static struct posix_lock_key key;
	TDB_DATA kbuf;

	memset(&key, '\0', sizeof(key));
	key.device = dev;
	key.inode = inode;
	kbuf.dptr = (char *)&key;
	kbuf.dsize = sizeof(key);
	return kbuf;
}

/*******************************************************************
 Convenience function to get a key from an fsp.
******************************************************************/

static TDB_DATA locking_key_fsp(files_struct *fsp)
{
	return locking_key(fsp->dev, fsp->inode);
}

/****************************************************************************
 Add an fd to the pending close tdb.
****************************************************************************/

static BOOL add_fd_to_close_entry(files_struct *fsp)
{
	TDB_DATA kbuf = locking_key_fsp(fsp);
	TDB_DATA dbuf;
	char *tp;

	dbuf.dptr = NULL;
	dbuf.dsize = 0;

	dbuf = tdb_fetch(posix_pending_close_tdb, kbuf);

	tp = SMB_REALLOC(dbuf.dptr, dbuf.dsize + sizeof(int));
	if (!tp) {
		DEBUG(0,("add_fd_to_close_entry: Realloc fail !\n"));
		SAFE_FREE(dbuf.dptr);
		return False;
	} else
		dbuf.dptr = tp;

	memcpy(dbuf.dptr + dbuf.dsize, &fsp->fh->fd, sizeof(int));
	dbuf.dsize += sizeof(int);

	if (tdb_store(posix_pending_close_tdb, kbuf, dbuf, TDB_REPLACE) == -1) {
		DEBUG(0,("add_fd_to_close_entry: tdb_store fail !\n"));
	}

	SAFE_FREE(dbuf.dptr);
	return True;
}

/****************************************************************************
 Remove all fd entries for a specific dev/inode pair from the tdb.
****************************************************************************/

static void delete_close_entries(files_struct *fsp)
{
	TDB_DATA kbuf = locking_key_fsp(fsp);

	if (tdb_delete(posix_pending_close_tdb, kbuf) == -1)
		DEBUG(0,("delete_close_entries: tdb_delete fail !\n"));
}

/****************************************************************************
 Get the array of POSIX pending close records for an open fsp. Caller must
 free. Returns number of entries.
****************************************************************************/

static size_t get_posix_pending_close_entries(files_struct *fsp, int **entries)
{
	TDB_DATA kbuf = locking_key_fsp(fsp);
	TDB_DATA dbuf;
	size_t count = 0;

	*entries = NULL;
	dbuf.dptr = NULL;

	dbuf = tdb_fetch(posix_pending_close_tdb, kbuf);

	if (!dbuf.dptr) {
		return 0;
	}

	*entries = (int *)dbuf.dptr;
	count = (size_t)(dbuf.dsize / sizeof(int));

	return count;
}

/****************************************************************************
 Get the array of POSIX locks for an fsp. Caller must free. Returns
 number of entries.
****************************************************************************/

static size_t get_posix_lock_entries(files_struct *fsp, struct posix_lock **entries)
{
	TDB_DATA kbuf = locking_key_fsp(fsp);
	TDB_DATA dbuf;
	size_t count = 0;

	*entries = NULL;

	dbuf.dptr = NULL;

	dbuf = tdb_fetch(posix_lock_tdb, kbuf);

	if (!dbuf.dptr) {
		return 0;
	}

	*entries = (struct posix_lock *)dbuf.dptr;
	count = (size_t)(dbuf.dsize / sizeof(struct posix_lock));

	return count;
}

/****************************************************************************
 Deal with pending closes needed by POSIX locking support.
 Note that posix_locking_close_file() is expected to have been called
 to delete all locks on this fsp before this function is called.
****************************************************************************/

int fd_close_posix(struct connection_struct *conn, files_struct *fsp)
{
	int saved_errno = 0;
	int ret;
	size_t count, i;
	struct posix_lock *entries = NULL;
	int *fd_array = NULL;
	BOOL locks_on_other_fds = False;

	if (!lp_posix_locking(SNUM(conn))) {
		/*
		 * No POSIX to worry about, just close.
		 */
		ret = SMB_VFS_CLOSE(fsp,fsp->fh->fd);
		fsp->fh->fd = -1;
		return ret;
	}

	/*
	 * Get the number of outstanding POSIX locks on this dev/inode pair.
	 */

	count = get_posix_lock_entries(fsp, &entries);

	/*
	 * Check if there are any outstanding locks belonging to
	 * other fd's. This should never be the case if posix_locking_close_file()
	 * has been called first, but it never hurts to be *sure*.
	 */

	for (i = 0; i < count; i++) {
		if (entries[i].fd != fsp->fh->fd) {
			locks_on_other_fds = True;
			break;
		}
	}

	if (locks_on_other_fds) {

		/*
		 * There are outstanding locks on this dev/inode pair on other fds.
		 * Add our fd to the pending close tdb and set fsp->fh->fd to -1.
		 */

		if (!add_fd_to_close_entry(fsp)) {
			SAFE_FREE(entries);
			return -1;
		}

		SAFE_FREE(entries);
		fsp->fh->fd = -1;
		return 0;
	}

	SAFE_FREE(entries);

	/*
	 * No outstanding POSIX locks. Get the pending close fd's
	 * from the tdb and close them all.
	 */

	count = get_posix_pending_close_entries(fsp, &fd_array);

	if (count) {
		DEBUG(10,("fd_close_posix: doing close on %u fd's.\n", (unsigned int)count ));

		for(i = 0; i < count; i++) {
			if (SMB_VFS_CLOSE(fsp,fd_array[i]) == -1) {
				saved_errno = errno;
			}
		}

		/*
		 * Delete all fd's stored in the tdb
		 * for this dev/inode pair.
		 */

		delete_close_entries(fsp);
	}

	SAFE_FREE(fd_array);

	/*
	 * Finally close the fd associated with this fsp.
	 */

	ret = SMB_VFS_CLOSE(fsp,fsp->fh->fd);

	if (saved_errno != 0) {
		errno = saved_errno;
		ret = -1;
	} 

	fsp->fh->fd = -1;

	return ret;
}

/****************************************************************************
 Debugging aid :-).
****************************************************************************/

static const char *posix_lock_type_name(int lock_type)
{
	return (lock_type == F_RDLCK) ? "READ" : "WRITE";
}

/****************************************************************************
 Delete a POSIX lock entry by index number. Used if the tdb add succeeds, but
 then the POSIX fcntl lock fails.
****************************************************************************/

static BOOL delete_posix_lock_entry_by_index(files_struct *fsp, size_t entry)
{
	TDB_DATA kbuf = locking_key_fsp(fsp);
	TDB_DATA dbuf;
	struct posix_lock *locks;
	size_t count;

	dbuf.dptr = NULL;
	
	dbuf = tdb_fetch(posix_lock_tdb, kbuf);

	if (!dbuf.dptr) {
		DEBUG(10,("delete_posix_lock_entry_by_index: tdb_fetch failed !\n"));
		goto fail;
	}

	count = (size_t)(dbuf.dsize / sizeof(struct posix_lock));
	locks = (struct posix_lock *)dbuf.dptr;

	if (count == 1) {
		tdb_delete(posix_lock_tdb, kbuf);
	} else {
		if (entry < count-1) {
			memmove(&locks[entry], &locks[entry+1], sizeof(struct posix_lock)*((count-1) - entry));
		}
		dbuf.dsize -= sizeof(struct posix_lock);
		tdb_store(posix_lock_tdb, kbuf, dbuf, TDB_REPLACE);
	}

	SAFE_FREE(dbuf.dptr);

	return True;

 fail:

	SAFE_FREE(dbuf.dptr);
	return False;
}

/****************************************************************************
 Add an entry into the POSIX locking tdb. We return the index number of the
 added lock (used in case we need to delete *exactly* this entry). Returns
 False on fail, True on success.
****************************************************************************/

static BOOL add_posix_lock_entry(files_struct *fsp, SMB_OFF_T start, SMB_OFF_T size, int lock_type, size_t *pentry_num)
{
	TDB_DATA kbuf = locking_key_fsp(fsp);
	TDB_DATA dbuf;
	struct posix_lock pl;
	char *tp;

	dbuf.dptr = NULL;
	dbuf.dsize = 0;

	dbuf = tdb_fetch(posix_lock_tdb, kbuf);

	*pentry_num = (size_t)(dbuf.dsize / sizeof(struct posix_lock));

	/*
	 * Add new record.
	 */

	pl.fd = fsp->fh->fd;
	pl.start = start;
	pl.size = size;
	pl.lock_type = lock_type;

	tp = SMB_REALLOC(dbuf.dptr, dbuf.dsize + sizeof(struct posix_lock));
	if (!tp) {
		DEBUG(0,("add_posix_lock_entry: Realloc fail !\n"));
		goto fail;
	} else
		dbuf.dptr = tp;

	memcpy(dbuf.dptr + dbuf.dsize, &pl, sizeof(struct posix_lock));
	dbuf.dsize += sizeof(struct posix_lock);

	if (tdb_store(posix_lock_tdb, kbuf, dbuf, TDB_REPLACE) == -1) {
		DEBUG(0,("add_posix_lock: Failed to add lock entry on file %s\n", fsp->fsp_name));
		goto fail;
	}

	SAFE_FREE(dbuf.dptr);

	DEBUG(10,("add_posix_lock: File %s: type = %s: start=%.0f size=%.0f: dev=%.0f inode=%.0f\n",
			fsp->fsp_name, posix_lock_type_name(lock_type), (double)start, (double)size,
			(double)fsp->dev, (double)fsp->inode ));

	return True;

 fail:

	SAFE_FREE(dbuf.dptr);
	return False;
}

/****************************************************************************
 Calculate if locks have any overlap at all.
****************************************************************************/

static BOOL does_lock_overlap(SMB_OFF_T start1, SMB_OFF_T size1, SMB_OFF_T start2, SMB_OFF_T size2)
{
	if (start1 >= start2 && start1 <= start2 + size2)
		return True;

	if (start1 < start2 && start1 + size1 > start2)
		return True;

	return False;
}

/****************************************************************************
 Delete an entry from the POSIX locking tdb. Returns a copy of the entry being
 deleted and the number of records that are overlapped by this one, or -1 on error.
****************************************************************************/

static int delete_posix_lock_entry(files_struct *fsp, SMB_OFF_T start, SMB_OFF_T size, struct posix_lock *pl)
{
	TDB_DATA kbuf = locking_key_fsp(fsp);
	TDB_DATA dbuf;
	struct posix_lock *locks;
	size_t i, count;
	BOOL found = False;
	int num_overlapping_records = 0;

	dbuf.dptr = NULL;
	
	dbuf = tdb_fetch(posix_lock_tdb, kbuf);

	if (!dbuf.dptr) {